Cruz Coronado applies to attend an exclusive school for explorers, the Explorer Academy, where his mother worked before dying in a mysterious lab accident. Plunged into a world of critical missions and code breaking, the 12-year-old embarks on a global hunt for a secret formula that could reveal his hidden past. But it might be difficult—especially when you don’t know who you can trust.

In the book Explorer Academy: The Nebula Secret, 12-year-old Cruz Coronado breaks secret codes in order to fight dangerous villains and solve mysteries.Test your code-breaking skills by cracking secret messages in the game below.